1 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
2 #ifndef __BPF_HELPERS__
3 #define __BPF_HELPERS__
4
5 /*
6 * Note that bpf programs need to include either
7 * vmlinux.h (auto-generated from BTF) or linux/types.h
8 * in advance since bpf_helper_defs.h uses such types
9 * as __u64.
10 */
11 #include "bpf_helper_defs.h"
12
13 #define __uint(name, val) int (*name)[val]
14 #define __type(name, val) typeof(val) *name
15 #define __array(name, val) typeof(val) *name[]
16
17 /*
18 * Helper macro to place programs, maps, license in
19 * different sections in elf_bpf file. Section names
20 * are interpreted by libbpf depending on the context (BPF programs, BPF maps,
21 * extern variables, etc).
22 * To allow use of SEC() with externs (e.g., for extern .maps declarations),
23 * make sure __attribute__((unused)) doesn't trigger compilation warning.
24 */
25 #if __GNUC__ && !__clang__
26
27 /*
28 * Pragma macros are broken on GCC
29 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55578
30 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90400
31 */
32 #define SEC(name) __attribute__((section(name), used))
33
34 #else
35
36 #define SEC(name) \
37 _Pragma("GCC diagnostic push") \
38 _Pragma("GCC diagnostic ignored \"-Wignored-attributes\"") \
39 __attribute__((section(name), used)) \
40 _Pragma("GCC diagnostic pop") \
41
42 #endif
43
44 /* Avoid 'linux/stddef.h' definition of '__always_inline'. */
45 #undef __always_inline
46 #define __always_inline inline __attribute__((always_inline))
47
48 #ifndef __noinline
49 #define __noinline __attribute__((noinline))
50 #endif
51 #ifndef __weak
52 #define __weak __attribute__((weak))
53 #endif
54
55 /*
56 * Use __hidden attribute to mark a non-static BPF subprogram effectively
57 * static for BPF verifier's verification algorithm purposes, allowing more
58 * extensive and permissive BPF verification process, taking into account
59 * subprogram's caller context.
60 */
61 #define __hidden __attribute__((visibility("hidden")))
62
63 /* When utilizing vmlinux.h with BPF CO-RE, user BPF programs can't include
64 * any system-level headers (such as stddef.h, linux/version.h, etc), and
65 * commonly-used macros like NULL and KERNEL_VERSION aren't available through
66 * vmlinux.h. This just adds unnecessary hurdles and forces users to re-define
67 * them on their own. So as a convenience, provide such definitions here.
68 */
69 #ifndef NULL
70 #define NULL ((void *)0)
71 #endif
72
73 #ifndef KERNEL_VERSION
74 #define KERNEL_VERSION(a, b, c) (((a) << 16) + ((b) << 8) + ((c) > 255 ? 255 : (c)))
75 #endif
76
77 /*
78 * Helper macros to manipulate data structures
79 */
80 #ifndef offsetof
81 #define offsetof(TYPE, MEMBER) ((unsigned long)&((TYPE *)0)->MEMBER)
82 #endif
83 #ifndef container_of
84 #define container_of(ptr, type, member) \
85 ({ \
86 void *__mptr = (void *)(ptr); \
87 ((type *)(__mptr - offsetof(type, member))); \
88 })
89 #endif
90
91 /*
92 * Compiler (optimization) barrier.
93 */
94 #ifndef barrier
95 #define barrier() asm volatile("" ::: "memory")
96 #endif
97
98 /* Variable-specific compiler (optimization) barrier. It's a no-op which makes
99 * compiler believe that there is some black box modification of a given
100 * variable and thus prevents compiler from making extra assumption about its
101 * value and potential simplifications and optimizations on this variable.
102 *
103 * E.g., compiler might often delay or even omit 32-bit to 64-bit casting of
104 * a variable, making some code patterns unverifiable. Putting barrier_var()
105 * in place will ensure that cast is performed before the barrier_var()
106 * invocation, because compiler has to pessimistically assume that embedded
107 * asm section might perform some extra operations on that variable.
108 *
109 * This is a variable-specific variant of more global barrier().
110 */
111 #ifndef barrier_var
112 #define barrier_var(var) asm volatile("" : "=r"(var) : "0"(var))
113 #endif
114
115 /*
116 * Helper macro to throw a compilation error if __bpf_unreachable() gets
117 * built into the resulting code. This works given BPF back end does not
118 * implement __builtin_trap(). This is useful to assert that certain paths
119 * of the program code are never used and hence eliminated by the compiler.
120 *
121 * For example, consider a switch statement that covers known cases used by
122 * the program. __bpf_unreachable() can then reside in the default case. If
123 * the program gets extended such that a case is not covered in the switch
124 * statement, then it will throw a build error due to the default case not
125 * being compiled out.
126 */
127 #ifndef __bpf_unreachable
128 # define __bpf_unreachable() __builtin_trap()
129 #endif
130
131 /*
132 * Helper function to perform a tail call with a constant/immediate map slot.
133 */
134 #if __clang_major__ >= 8 && defined(__bpf__)
135 static __always_inline void
bpf_tail_call_static(void * ctx,const void * map,const __u32 slot)136 bpf_tail_call_static(void *ctx, const void *map, const __u32 slot)
137 {
138 if (!__builtin_constant_p(slot))
139 __bpf_unreachable();
140
141 /*
142 * Provide a hard guarantee that LLVM won't optimize setting r2 (map
143 * pointer) and r3 (constant map index) from _different paths_ ending
144 * up at the _same_ call insn as otherwise we won't be able to use the
145 * jmpq/nopl retpoline-free patching by the x86-64 JIT in the kernel
146 * given they mismatch. See also d2e4c1e6c294 ("bpf: Constant map key
147 * tracking for prog array pokes") for details on verifier tracking.
148 *
149 * Note on clobber list: we need to stay in-line with BPF calling
150 * convention, so even if we don't end up using r0, r4, r5, we need
151 * to mark them as clobber so that LLVM doesn't end up using them
152 * before / after the call.
153 */
154 asm volatile("r1 = %[ctx]\n\t"
155 "r2 = %[map]\n\t"
156 "r3 = %[slot]\n\t"
157 "call 12"
158 :: [ctx]"r"(ctx), [map]"r"(map), [slot]"i"(slot)
159 : "r0", "r1", "r2", "r3", "r4", "r5");
160 }
161 #endif
162
163 enum libbpf_pin_type {
164 LIBBPF_PIN_NONE,
165 /* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */
166 LIBBPF_PIN_BY_NAME,
167 };
168
169 enum libbpf_tristate {
170 TRI_NO = 0,
171 TRI_YES = 1,
172 TRI_MODULE = 2,
173 };
174
175 #define __kconfig __attribute__((section(".kconfig")))
176 #define __ksym __attribute__((section(".ksyms")))
177 #define __kptr __attribute__((btf_type_tag("kptr")))
178 #define __kptr_ref __attribute__((btf_type_tag("kptr_ref")))
179
180 #ifndef ___bpf_concat
181 #define ___bpf_concat(a, b) a ## b
182 #endif
183 #ifndef ___bpf_apply
184 #define ___bpf_apply(fn, n) ___bpf_concat(fn, n)
185 #endif
186 #ifndef ___bpf_nth
187 #define ___bpf_nth(_, _1, _2, _3, _4, _5, _6, _7, _8, _9, _a, _b, _c, N, ...) N
188 #endif
189 #ifndef ___bpf_narg
190 #define ___bpf_narg(...) \
191 ___bpf_nth(_, ##__VA_ARGS__, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
192 #endif
193
194 #define ___bpf_fill0(arr, p, x) do {} while (0)
195 #define ___bpf_fill1(arr, p, x) arr[p] = x
196 #define ___bpf_fill2(arr, p, x, args...) arr[p] = x; ___bpf_fill1(arr, p + 1, args)
197 #define ___bpf_fill3(arr, p, x, args...) arr[p] = x; ___bpf_fill2(arr, p + 1, args)
198 #define ___bpf_fill4(arr, p, x, args...) arr[p] = x; ___bpf_fill3(arr, p + 1, args)
199 #define ___bpf_fill5(arr, p, x, args...) arr[p] = x; ___bpf_fill4(arr, p + 1, args)
200 #define ___bpf_fill6(arr, p, x, args...) arr[p] = x; ___bpf_fill5(arr, p + 1, args)
201 #define ___bpf_fill7(arr, p, x, args...) arr[p] = x; ___bpf_fill6(arr, p + 1, args)
202 #define ___bpf_fill8(arr, p, x, args...) arr[p] = x; ___bpf_fill7(arr, p + 1, args)
203 #define ___bpf_fill9(arr, p, x, args...) arr[p] = x; ___bpf_fill8(arr, p + 1, args)
204 #define ___bpf_fill10(arr, p, x, args...) arr[p] = x; ___bpf_fill9(arr, p + 1, args)
205 #define ___bpf_fill11(arr, p, x, args...) arr[p] = x; ___bpf_fill10(arr, p + 1, args)
206 #define ___bpf_fill12(arr, p, x, args...) arr[p] = x; ___bpf_fill11(arr, p + 1, args)
207 #define ___bpf_fill(arr, args...) \
208 ___bpf_apply(___bpf_fill, ___bpf_narg(args))(arr, 0, args)
209
210 /*
211 * BPF_SEQ_PRINTF to wrap bpf_seq_printf to-be-printed values
212 * in a structure.
213 */
214 #define BPF_SEQ_PRINTF(seq, fmt, args...) \
215 ({ \
216 static const char ___fmt[] = fmt; \
217 unsigned long long ___param[___bpf_narg(args)]; \
218 \
219 _Pragma("GCC diagnostic push") \
220 _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \
221 ___bpf_fill(___param, args); \
222 _Pragma("GCC diagnostic pop") \
223 \
224 bpf_seq_printf(seq, ___fmt, sizeof(___fmt), \
225 ___param, sizeof(___param)); \
226 })
227
228 /*
229 * BPF_SNPRINTF wraps the bpf_snprintf helper with variadic arguments instead of
230 * an array of u64.
231 */
232 #define BPF_SNPRINTF(out, out_size, fmt, args...) \
233 ({ \
234 static const char ___fmt[] = fmt; \
235 unsigned long long ___param[___bpf_narg(args)]; \
236 \
237 _Pragma("GCC diagnostic push") \
238 _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \
239 ___bpf_fill(___param, args); \
240 _Pragma("GCC diagnostic pop") \
241 \
242 bpf_snprintf(out, out_size, ___fmt, \
243 ___param, sizeof(___param)); \
244 })
245
246 #ifdef BPF_NO_GLOBAL_DATA
247 #define BPF_PRINTK_FMT_MOD
248 #else
249 #define BPF_PRINTK_FMT_MOD static const
250 #endif
251
252 #define __bpf_printk(fmt, ...) \
253 ({ \
254 BPF_PRINTK_FMT_MOD char ____fmt[] = fmt; \
255 bpf_trace_printk(____fmt, sizeof(____fmt), \
256 ##__VA_ARGS__); \
257 })
258
259 /*
260 * __bpf_vprintk wraps the bpf_trace_vprintk helper with variadic arguments
261 * instead of an array of u64.
262 */
263 #define __bpf_vprintk(fmt, args...) \
264 ({ \
265 static const char ___fmt[] = fmt; \
266 unsigned long long ___param[___bpf_narg(args)]; \
267 \
268 _Pragma("GCC diagnostic push") \
269 _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \
270 ___bpf_fill(___param, args); \
271 _Pragma("GCC diagnostic pop") \
272 \
273 bpf_trace_vprintk(___fmt, sizeof(___fmt), \
274 ___param, sizeof(___param)); \
275 })
276
277 /* Use __bpf_printk when bpf_printk call has 3 or fewer fmt args
278 * Otherwise use __bpf_vprintk
279 */
280 #define ___bpf_pick_printk(...) \
281 ___bpf_nth(_, ##__VA_ARGS__, __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, \
282 __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, \
283 __bpf_vprintk, __bpf_vprintk, __bpf_printk /*3*/, __bpf_printk /*2*/,\
284 __bpf_printk /*1*/, __bpf_printk /*0*/)
285
286 /* Helper macro to print out debug messages */
287 #define bpf_printk(fmt, args...) ___bpf_pick_printk(args)(fmt, ##args)
288
289 #endif
290